1. Field of the Invention
This invention relates to generally to wound healing. In particular, the invention relates to wound healing with pressures altered both positively and negatively from atmospheric.
More specifically this invention is directed at apparatuses and methods that utilize layered intermediate material constructs, high gas-permeable cover constructs and pressure monitoring/control systems which are more convenient, safe and efficient for the clinician, more comfortable and less painful for the patient, and result in improved efficacy versus those of the prior art.
2. Background of the Invention
The need to rapidly close acute and chronic wounds has been a focus of research since the dawn of medical practice. The background art is characterized by therapeutic strategies utilizing pressures altered from atmospheric conditions. Such strategies have been practiced by clinicians for both acute and chronic wounds for over a hundred years. Positive pressure strategies began expanded utilization least by the early 1800's, while negative pressure wound therapy began institutional practice at least as far back as the early 1980's.
Positive pressure wound therapy began by employing large chambers that encapsulated the entire patient. While more locally focused pressures have been attempted, they proved problematic for the relatively high pressures utilized. Conversely, to date negative pressure wound therapy has been developed as a local site methodology, specific to a peripheral zone around the wound bed. Likewise, the present invention limits its application to the local tissue of and around the wound; however, it can utilize both negative pressures and positive pressures.
The following core features are common among the negative pressure wound therapy configurations known in the art, which employ a local site application methodology:                a covering means adapted to protect a wound from contamination and/or trauma;        a sealing means, optionally designed as a part of the covering means, for establishing intimate but reversible contact with the perimeter of said covering to surrounding skin surfaces of said wound, thereby creating an encapsulated space, including the wound bed under said covering;        the sealing means further providing a seal competent enough to provide treatment of the wound with pressures purposefully altered to those lower than atmospheric;        a pressure altering means for interfacing negative pressures from a source with the said encapsulated space to lower the pressure therein as desired, said pressure altering means working in combination with said covering and sealing means to maintain the so desired encapsulated space pressures;        the pressure altering means comprising a proximal end, a medial section and a distal end;        a negative pressure source for delivering the initial pressure differential to the pressure altering means; and optionally at least one of the following:                    a. the pressure altering means further consisting of a proximal end with direct physical access to the encapsulated space through an opening or conduit through said covering, and a distal end connected to the proximal end via a medial section, such distal end further adapted for connection to a negative pressure source; or            b. the pressure altering means further consisting of a proximal end with direct physical access to the encapsulated space through a passage created between skin and sealing means of said covering, and a distal end connected to the proximal end via a medial section, such distal end further adapted for connection to a negative pressure source; or            c. the pressure altering means further consisting of a proximal end with indirect access to the encapsulated space though a void or opening in said cover, and a distal end connected to the proximal end via a medial section, such distal end further adapted for connection to a negative pressure source; or            d. the pressure altering means further consisting of a proximal end with indirect access to the encapsulated space through a passage created between skin and sealing means of said covering, and a distal end connected to the proximal end via a medial section, such distal end further adapted for connection to a negative pressure source.                        
The apparatus above generically encompasses the core features of the historical apparatuses in the literature and prior art.
3. Related Art
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention; however, the following references were considered related.
Journal article “The vacuum effect in the surgical treatment of purulent wounds” by Kostiuchenok, II; Kolker, V A Karlov V A, et al.: Vestnik Khirurgii 1986 describes an intermittent manual application of minimal negative pressure to reduce bacterial counts and heal stubborn wounds.
Journal article “Vacuum therapy in the treatment of purulent lactation mastitis” by Davydov u A. Malafeeva, E. V., Smirnov A. P.: Vestnik Khirurgii Imeni I. I.—Grekova 1986 presents the retrospective results of over 100 patients presenting with purulent mastitis. The authors describe the techniques of intermittent application of various negative pressures and durations as used in their clinic since 1980, as well as efficacy results regarding these techniques.
Journal article “Active wound drainage” by Usupov, Y N; Yepifanov, M V: Vestnik Khirugii 1987 describes the authors methodology and results for determining apparent threshold and maximum negative pressures which attempt to project a therapeutic index for negative pressures from an animal model.
Journal article “The Bacteriological and cytological assessment of vacuum therapy of purulent wounds” by Davydov Yu A., Larichev A. B., Menkov, K. G.: Vestnik Khirurgii Imeni-i—Grekova 1988 describes the techniques for intermittent application of various negative pressures and durations and demonstrates the faster progression through healing stages of these patients compared to controls.
Journal article “Effective management of incisional and cutaneous fistulae with closed suction wound drainage” by Chariker, M E; Jeter, K F, et al.: Contemporary Surgery 1989 authors describe specific dressings and treatment methodologies including drains, screens, packings and covers which are readily available to world wide clinicians and readily adaptable to negative pressure therapy. The authors report on the training and efficacy of these methodologies for a specific hard to heal surgical wounds, namely fistulae complicated wounds.
Journal article “Concepts for clinical biological management of the wound process in the treatment of purulent wounds using vacuum therapy” by Davydov, Y A; Larichev, A B, Abramov A Y, et al.: Vestnik Khirugii 1991 authors report on expansion of applications of negative pressure techniques to various acute and chronic wounds as well as patient populations as expanded since their previous publication. Authors also describe attributes of negative pressure therapy that may explain its efficacy.
U.S. Pat. No. 4,382,441 issued in the name of Svedman; Pal teaches the composition of a wound dressing designed for irrigation treatment of a wound combined with suction. The dressing comprises (a) an impermeable cover, (b) at least two openings at opposing ends of the dressing and formed through the central section of the cover for subsequent insertion of both an irrigation tube and a suction tube, and (c) a porous intermediate material. No pressures are disclosed in this patent, but the implied intent is to keep the irrigation inlet, when operable, at atmospheric or very low positive pressure to avoid expansion and dislocation of the cover. Consequently the implied optimal suction outlet pressure, when operable, is slightly greater than the irrigation inlet pressure, thereby drawing and distributing the irrigant evenly through the porous intermediate material and evenly across the wound bed in a controlled delivery manner, without build up of the irrigant.
U.S. Pat. No. 4,969,880 issued in the name of Zamierowski; David S. teaches the composition of a wound dressing designed for negative pressure treatment of a wound that includes a semi-permeable cover with an adhesive sealing means, an opening formed through the central section of the cover for the introduction of a PAM, said PAM adapted for connection to a negative pressure source or a fluid source for introducing fluids. This patent also teaches a variety of intermediate materials which can be placed between the wound bed and the PAM under the cover. A method of wound treatment with the said dressing is also disclosed.
U.S. Pat. No. 5,527,293 issued in the name of Zamierowski; David S. teaches a specific method for fastening suction tubes (i.e. drains) to wound dressings designed for negative pressure wound therapy. Briefly, this fastening method for treating wounds with negative pressure comprises (a) applying a dressing to the wound; (b) adhering a polymer cover/seal to a foam material inserted between the cover and tissue; (c) applying negative pressure to the wound; and (d) directing fluid flow with the polymer cover/seal from wound surface through the foam material. The said dressing comprises preferably a semi-permeable adhesive polymer cover/seal.
U.S. Pat. No. 5,645,081 issued in the name of Argenta et al. teaches another method for wound treatment utilizing negative pressure, but utilizes an impermeable cover rather than semi-permeable, contrary to U.S. Pat. No. 4,969,880. The patent further teaches the use of intermediate materials in combination with impermeable covers with the PAM contained within or underneath the intermediate materials.
U.S. Pat. No. 5,636,643 issued in the name of Argenta et al. teaches another method for wound treatment utilizing negative pressure, but utilizes an impermeable cover rather than semi-permeable, contrary to U.S. Pat. No. 4,969,880. The patent further teaches the use of negative pressure adapted to specific wound types and specific durations of therapy.
U.S. Pat. No. 6,135,116 issued in the name of Vogel et al. teaches a method and apparatus for combining intermittent pneumatic compression and negative pressure wound therapy.
U.S. Pat. No. 6,553,998 issued in the name of Heaton et al. teaches negative pressure wound therapy that utilizes the combination of a suction head and a cover. More specifically, the suction head is designed with projections on the bottom flange, which prevent sealing or blockage of the suction head by providing flow channels for liquids to exit the wound via a PAM.
PCT/US2007/019033 filed in the name of Kennedy et al, the same inventors of this filing, teaches apparatuses and methods for treating wounds with altered pressures. Briefly, and relevant to the inventions and disclosures contained herein, the previous PCT filing discloses (a) PAM designs, especially relative to designs and components for terminal connections to altered pressure dressings; (b) anti-infective and anti-ingrowth compositions for use with altered pressure therapy; (c) specific canister designs; (d) intermediate material compositions; and (e) pressure sensing feedback designs.
Consequently, a need has been demonstrated for the invention which provides methods, apparatuses and compositions that: (a) improve the performance of altered pressure wound therapy (b) make the treatments more comfortable for the patient, and (c) make the administration of the treatment more convenient for clinicians. These improvements collectively result in improved efficacy, improved compliance, improved safety and improved performance, while limiting clinical errors in treatment.